Effect pigments, also known as pearlescent pigments or nacreous pigments, are used to impart a pearlescent luster, metallic luster, and/or multi-color effect approaching iridescence, to a material. For instance, red effect pigments based on flake-form substrates are important in cosmetics. Due to strict governmental regulation, the primary red effect pigments for cosmetic applications are carmine and Fe2O3-based pigments.
Carmine is a red organic pigment obtained from carminic acid produced by scale insects such as cochineals. Carmine can contribute to bluish-red shades. Effect pigments made with carmine often have a short shelf-life due to the degradation of carmine resulting from its uv-light susceptibility. In addition, there is concern that carmine might cause allergic reactions and therefore be hazardous when used as a dye in foodstuffs or cosmetics.
Fe2O3-based effect pigments tend to be very stable and not subject to decomposition the way carmine effect pigments are. The absorption component of hematite-Fe2O3 contributes red-orange hues. However, Fe2O3-based effect pigments do not provide the color intensity and brightness of carmine-based pigments.
There is an on-going need in the art for red pigment compositions with improved properties.